After your make World BOOTSTRAPCFLAGS="... succeed,
make installto install in /usr/X11R6. Make sure you have enough space, and /usr/X11R6 exists either as a directory or a symlink to another directory maybe in another filesystem.
make install.manto install the compressed nroff versions of the manual pages into /usr/X11R6/man. This directory will be generated if it doesn't exist.
make install.linkkitto install the server binary LinkKit into /usr/X11R6/lib/Server.
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You could tune the Kernel using the command-file /usr/X11R6/lib/X11/etc/xf86install This will increase the available pseudo devices, some Tunable Parameters and install some files to use inside sysadm. You could also install some additional Fonts and Terminal files.<hr>